Dermatology Flashcards
(169 cards)
1
Q
Circinate balanitis is a manifestation of which disease?
A
Reactive arthritis
2
Q
Keratoderma blenorrhagica is a manifestation of which disease?
A
Reactive arthritis
May resemble psoriasis. Commonly found on palms and soles
5
Q
Which dermatological conditions are associated with reactive arthritis?
A
Balanitis circinata
Keratoma blenorrhagicum
6
Q
List 4 causes of erythema nodosum
A
- Post-strep throat
- Sarcoidosis
- Tuberculosis
- Pregnancy
- IBD
7
Q
Pyoderma gangrenosum is found most commonly in which disease?
A
IBD
8
Q
List 4 distinctive features of Kawasaki disease
A
- C - conjunctivitis (no exudate)
- rash (polymorphous, originating on trunk)
- adenopathy (cervical lymphadenopathy)
- strawberry tongue (+ cracked and red lips)
- hands and feet (oedema and erythema)
9
Q
What is the major complication of Kawasaki disease and when does it occur?
A
Coronary artery aneurysm
2-3 weeks after symptom onset
10
Q
Koplik spots are found in which disease?
A
Measles
(prodromal stage, 1-2 days before the rash)
11
Q
Explain the progression of the rash in measles
A
Begins on the face and behind the ears 2 weeks after exposure
Spreads to the trunk and extremities within 24-36 hours
Lasts 3-4 days
12
Q
What is this sign and when is it present?
A
Rubella
Forchheimer sign
Petechiae on the soft palate and uvula during the prodromal period
13
Q
A sandpaper-like textured rash is characteristic of which disease?
A
Scarlet fever
14
Q
Where are Pastia’s lines are found?
Which disease are they characteristic of?
A
Scarlet fever
Groin, underarm, elbow creases
15
Q
What causes hand, foot and mouth disease?
A
Coxsackie A
16
Q
What is the pathophysiology of HSP?
A
Exposure to allergen/antigen e.g. infection, drugs → stimulation of IgA production → deposition of IgA immune complexes in vascular walls e.g. skin, GI tract, joints, kidneys → activation of complement → vascular inflammation and damage
17
Q
What is the most common infection to precede HSP?
A
URTI caused by group A streptococcus
18
Q
A
Roseola
19
Q
A
Scarlet fever
20
Q
A
Rubella
21
Q
A
Measles
22
Q
A
Erythema infectiosum
23
Q
What is an enanthem?
A
Rash on mucous membranes
24
Q
Identify two rashes in children which are characteristically cephalocaudal
A
- Measles
- Rubella (German measles)
(head to tail)
25
Q
What are the characteristic features of a measles prodrome?
A
Three c’s
- Conjunctivitis
- Cough
- Coryza
* This respiratory prodrome is characteristic and distinctive*
26
Q
What is the treatment for Kawasaki disease?
A
IV immunoglobulin
High dose aspirin (antiplatelet effects)
27
Which age groups are at highest risk of meningococcal disease?
Children 6 months - 4 years
Teenagers 15 - 19 years
28
What is the pathophysiology of the rash in meningococcal disease?
Bacterial toxin --\> disseminated vasculitis --\> leakage of RBCs into tissue --\> NON-BLANCHING rash (petechiae which progress to purpura)
29
What causes meningococcal disease?
Neisseria meningitidis
30
When does the rash in erythema infectiosum occur?
After the slapped cheeks
31
What causes roseola?
Herpes virus 6
32
A high temperature which resolves and is followed by a rash is characteristic of which disease?
Roseola
33
Oedematous eyelids and a bulging fontanelle is associated with which childhood illness/rash?
Roseola
34
Which childhood rash is also associated with tender and swollen retroauricular, occipital and posterior cervical lymph nodes
Rubella
35
What is the pathophysiology of scarlet fever?
Bacterial toxin-mediated
Group A streptococcus
Occurs in \<10% of streptococcal tonsillopharyngitis
36
Where does the rash of scarlet fever start?
Below the ears, neck, chest, armpits and groin
37
Which medication is contraindicated in people with EBV?
Ampicillin
Leads to a morbilliform rash
38
What is the triad of congenital rubella syndrome?
1. Cataracts
2. Cochlear defect (bilateral sensorial hearing loss)
3. Cardiac defect (patent dustus arteriosus, pulmonary artery stenosis)
39
What type of hypersensitivity reaction is allergic contact dermatitis?
IV
40
What causes impetigo?
*Staphylococci* or group A B-haemolytic *streptococci*
41
What causes erythrasma?
*Corynebacterium minutissimum*
42
Which rash is coral-red under Wood's lamp?
Erythrasma
43
What is the treatment for recent-onset, localised tinea?
Terbinafine gel
44
What are two treatment options for cutaneous candidiasis?
"-azole" cream
Nystatin
45
What causes pityriasis versicolour?
Malassezia yeast
46
What is the treatment for pityriasis versicolour?
"-azole" cream
47
When is the typical onset of atopic dermatitis?
3 to 6 months of age
48
What are 3 treatment options for atopic dermatitis?
1. Gentle skin care
2. Topical corticosteroids
3. Topical calcineurin inhibitors
4. Antipruritics
49
What causes skin pigmentation in venous stasis eczema?
Haemosiderin deposition
RBCs breakdown and release haemosiderin
50
Dyshidrotic dermatitis
51
What are 3 dermatological complications of atopic dermatitis?
1. Impetigo
2. Eczema herpeticum
3. Keratosis pilaris
4. Ichthyosis vulgaris/palmar hyperlinearity
5. Dennie-Morgan folds
52
Keratosis pilaris
Abnormal keratinisation of the lining of the upper portion of the hair follicle. Scale fills the follicle instead of exfoliating.
53
Ichthyosis vulgaris
Associated with atopic dermatitis
54
Dennie-Morgan folds
55
Eczema herpeticum
Disseminated herpes 1/2 infection w/ fever + rash + lymphadenopathy
Atopic people are susceptible
56
What is the pathological hallmark of dermatitis?
Spongiosis
Widening of the space between keratinocytes due to oedema
57
What is erythema multiforme?
Rare, acute hypersensitivity reaction most commonly triggered by herpes simplex infections
58
Keratosis pilaris
59
How is scabies treated?
Permethrin
60
What is the pathophysiology of serum sickness?
Type III hypersensitivity
Due to anti-toxin or anti-venom administration
Fever, urticarial rash, arthralgia, lymphadenopathy, gastrointestinal symptoms
61
Chicken pox
62
Name 2 less sedating antihistamines
Cetirizine (least sedating/Zyrtec)
Desloratadine
Fexofenadine
Loratadine
63
In which two instances is angioedema not IgE-mediated?
Direct mast-cell activation e.g. NSAIDs
Bradykinin-mediated e.g. ACEi-induced (impaired breakdown), hereditary angioedema (C1 esterase inhibitor deficiency)
64
What are indications for antiviral therapy for chicken pox?
Immunosuppression
Infection in people aged 13 and older
*Acyclovir*
65
What is the most common autoimmune blistering disease?
Bullous pemphigoid
66
When is the peak incidence of bullous pemphigoid?
\>60 years
67
When is the peak incidence of pemphigus vulgaris?
40-60 years
68
When is the peak incidence of dermatitis herpetiformis?
15-40 years
69
Which autoimmune condition is strongly linked to dermatitis herpetiformis?
Coeliac disease
70
How is dermatitis herpetiformis treated?
Dapsone
Gluten-free diet
71
How is pemphigus vulgaris treated?
High dose systemic steroids
Immunosuppression
72
How is bullous pemphigoid treated?
High-dose topical steroids
Systemic glucocorticoids and immunosuppressants can be used if needed
73
What is Nikolsy's sign
Rubbing of the skin → upper epidermal layer slips away from lower layer → separation of the epidermis → blistering
74
What are 3 conditions with a positive Nikolsky's sign?
1. Pemphigus vulgaris
2. TEN
3. SJS
4. Staphylococcal scalded skin syndrome
5. Scalding bullous impetigo
75
What are two conditions with Tzanck cells in microscopic evaluation?
1. Pemphigus vulgaris
2. Herpes simplex 1
3. Varicella zoster
4. CMV
5. SSSS
76
Which condition is this?
Prodrome (urticarial lesions weeks to months beforehand)
Large, tense, subepidermal blisters
Intensely pruritic
Bullous pemphigoid
77
Which condition is this?
Spontaneous onset of painful flaccid, intraepidermal blisters → lesions rupture and become confluent → erosions and crusts
Lesions present first on the oral mucosa then on body parts exposed to pressure e.g. intertriginous areas
Pruritis is absent
Pemphigoid vulgaris
78
How does mucosal involvement differentiate SJS/TEN from SSSS?
Mucous membranes are spared in SSSS
Mucous membranes are almost always involved in SJS/TEN
79
How are SJS/TEN differentiated?
The proportion of skin involvement
\<10%: SJS
10-30%: overlap
\>30%: TEN
80
What is the strongest risk factor for SJS?
HIV infection (100x risk increase, 5% of patients)
81
What are 4 drugs/drug classes that can cause SJS/TEN?
1. Antibiotics (sulfonamides)
2. Corticosteroids
3. Antiretrovirals
4. Antiepileptics
5. Allopurinol
6. Sulfasalazine
82
When is the peak incidence of staphylococcal scalded skin syndrome (SSSS)?
Children \< 6 years (98%)
83
How does the quality of bullae vary between bullous pemphigoid and pemphigus vulgaris?
Bullous pemphigoid: tense, do not rupture easily
Pemphigus vulgaris: flaccid, rupture and crust
84
Which condition is associated with autoimmune destruction of hemidesmosomes that attach basal keratinocytes to the underlying basement membrane
Bullous pemphigoid
85
How do lesions from pemphigus vulgaris resolve?
Bullae rupture → crusting → hyperpigmentation without scarring
86
Discoid lupus erythematosus
87
What is the risk of progression from discoid lupus erythematosus to SLE?
10-15%
88
How do lesions from discoid lupus erythematosus heal?
Scar tissue with central atrophy
89
Subacute cutaneous lupus erythematosus
Photosensitive annular plaques
90
Which antibodies are associated with discoid lupus erythematosus?
None (often ANA and anti-Ro negative)
91
Which antibodies are associated with subacute cutaneous lupus erythematosus?
Anti-Ro antibodies
92
What is the pathophysiology of pemphigus vulgaris?
IgG antibodies against desmoglein 1 and 3 (mediate keratinocyte adherence)
93
Which of the autoimmune blistering conditions typically first presents with mucosal lesions?
Pemphigus vulgaris
## Footnote
* Lesions begin on the mucosa and spread to intertriginous areas*
* Bullous pemphigoid and dermatitis herpetiformis rarely have mucosal involvement*
94
Which of the autoimmune blistering conditions present with pruritis?
* Bullous pemphigoid*
* Pemphigoid vulgaris*
* Dermatitis herpetiformis*
Bullous pemphigoid - intensely pruritic
Pemphigoid vulgaris - pruritis absent
Dermatitis herpetiformis - intensely pruritic
95
Where is the most common place for scabies lesions to be seen?
Interdigital web spaces
96
Which layer of the skin is affected by urticaria?
Dermis
Normal epidermis (no spongiosis or hyperplasia)
97
Which layer of the skin is affected by angioedema?
Subcutaneous and submucosal surfaces - **beneath the dermis**
98
How are the areas affected by angioedema and urticaria different?
Angioedema - skin and mucosa, including eyelids and lips
Urticaria - skin only
99
How is pain, tenderness and pruritis different in angioedema and urticaria?
Urticaria - itch, no pain or tenderness
Angioedema - pain and tenderness, no itch
100
What causes hereditary angioedema?
Congenital C1 esterase inhibitor deficiency
## Footnote
*Leads to a buildup of bradykinin*
101
Target lesions are characteristic of which disease?
Erythema multiform
1. Centre: dusky or dark red with blister or crust
2. Middle: pale pink, raised due to oedema
3. Outermost: bright red
102
List 2 diseases which exhibit the Koebner phenomenon
1. Psoriasis
2. Lichen planus
103
What is Auspitz sign and when is it positive?
Removal of scale → small bleeding points
Psoriasis
104
Which four phenomenon contribute to the pathogenesis of acne?
1. Hyperplasia of the sebaceous glands
2. Hyperkeratinisation
3. Propionibacterium acnes proliferation
4. Inflammation
105
Is pemphigus vulgaris subrabasal or subepidermal?
Suprabasal
106
Is bullous pemphigoid suprabasal or subepidermal?
Subepidermal
107
What is the gold standard for diagnosis of an autoimmune blistering condition?
Direct immunofluorescence
## Footnote
*Allows for the detection of antibody or complement deposition within the skin*
108
What are 3 potential exacerbating factors for pemphigus vulgaris?
1. Drugs (ACEi, phenobarbital, penicillin)
2. Viruses
3. UV
4. Diet (onion, garlic, leaks)
109
What is the pathophysiology of pemphigus vulgaris?
Antibodies against desmoglein 3 and 1
Desmosomes cause keratinocyte adherence in the stratum basale
110
What is the pathophysiology of bullous pemphigoid?
Antibodies against the bullous pemphigoid antigen in the basement membrane
Destruction of hemidesmosome-associated proteins
Hemidesmosomes attach keratinocytes to the ECM
111
What is the pathophysiology of dermatitis herpetiformis?
Cross reactivity of IgA anti-tissue transglutaminase with epidermal tissue-transglutaminase in the basement membrane
112
What is DRESS syndrome?
Drug Reaction with Eosinophilia and Systemic Symptoms
113
Which drug class most commonly causes DRESS?
Antiepileptics
## Footnote
*Also xanthine oxidase inhibtiors and sulfonamides*
114
What is the mechanism of acitretin (neotigason) in treating psoriasis?
Reverses epidermal proliferation and increased keratinisation seen in hyperkeratotic disorders
115
What is acantholysis?
The loss of intercellular connections, such as desmosomes, resulting in loss of cohesion between keratinocytes
116
What types of cells are seen on a Tzanck smear?
Giant multinucleated cell secondary to acantholysis
117
What does direct immunofluorescence detect?
Antibody deposition
118
What is the pathophysiology of SSSS?
Staphylococcus epidermolytic toxins A and B bind to desmoglein 1, impairing keratinocyte adherence
## Footnote
*→ acantholysis + Tzanck cells*
119
What are histological features of urticaria?
1. Superficial dermal oedema
2. Dilated blood vessels with perivascular inflammatory cells
3. Normal epidermis
120
What are the histological features of eczema?
1. Spongiosus
2. Superficial perivascular lymphocytic infiltrate
121
What is the pathophysiology of psoriasis?
Increased keratinocyte proliferation
→ acanthosis (thickening of the stratum spinosum)
→ parakeratosis (retention of nucleated keratinocytes in the stratum corneum)
122
Scabies
123
Pemphigus vulgaris
Deposition of immunoglobulin and complement along keratinocyte membranes gives a "fish-net" appearance
124
Bullous pemphigoid
Deposition of linear IgG and C3 along the dermoepidermal junction
Bullous pemphigoid antigen causes subepidermal separation
125
Where is pain from the gallbladder referred to?
Right shoulder
126
What is poikiloderma?
Skin with areas of hypopigmentation, hyperpigmentation, telangiectasias and atrophy
Commonly in sun-exposed areas
127
What is the shawl sign?
Poikiloderma found on the upper back, characteristic of dermatomyositis
128
What is the V sign?
Poikiloderma in the neck and upper chest, characteristic of dermatomyositis
*Proposed mechanism: complement-induced microvascular damage*
129
What are 2 diseases associated with calcinosis cutis?
Systemic sclerosis (particularly limited)
Dermatomyositis
*SLE*
130
A heliotrope rash and Gottron's papules are characteristic of which disease?
Dermatomyositis
131
What are periungual telangiectasias suggestive of?
Autoimmune connective tissue diseases
SLE, scleroderma, dermatomyositis
132
What is onycholysis?
Separation of the nail plate from the nail bed
*May be a feature of psoriasis*
133
What are 3 psoriatic nail changes?
1. Pitting of the nail bed
2. Subungual hyperkeratosis
3. Onycholysis (nail lifting)
4. Oil drops and salmon patches
5. Splinter haemorrhages
134
What is the proposed mechanism of dactylitis in spondyloarthropathies?
Enthesitis → inflammatory cytokines → synovitis and swelling of surrounding structures
135
Where are rheumatoid nodules most commonly found?
Extensor surfaces
136
What is the pathophysiology of rheumatoid nodules?
Repeated trauma → local vascular damage → endothelial injury + IgM RF immune complex formation → complement → inflammation → granuloma formation
137
How are localised impetigo lesions treated in non-remote community settings?
Mupirocin topically
138
How are multiple/recurrent impetigo lesions treated in non-remote community settings?
Di/flucloxacillin orally
139
How is impetigo in remote community settings and Northern Australia treated?
Benzathine penicillin IM as a single dose
OR
Trimethoprim + sulfamethoxazole
140
What are three ways of diagnosing prior GAS infection?
1. Positive throat culture for group A beta-haemolytic streptococci
2. Positive rapid streptococcal antigen
3. Elevated or rising antistreptococcal antibody titre - either antistreptolysin O (ASO) or anti-deoxyribonuclease B (ADB)
141
Which immune cell predominates in the infiltrate of bullous pemphigoid?
Eosinophils
142
What is eczema herpeticum?
Disseminated herpes 1/2 infection w/ fever + rash + lymphadenopathy
143
What is crusted/Norwegian scabies?
Highly contagious super infestation with *Sarcoptes scabiei var hominis*
144
What are 5 risk factors for crusted scabies? (*Sarcoptes scabiei var hominis* )
1. Increased age
2. Dementia
3. Down syndrome
4. HIV
5. SLE
6. Long-term corticosteroid or immunosuppressant use
7. Institutional accommodation e.g. prisons, nursing homes
8. Lymphoma
145
What causes pityriasis rosea?
Herpes 6 and 7
146
What is miliaria?
Sweat rash
Blockage and/or inflammation of eccrine sweat ducts
Frequently seen in hot, humid or tropical climates
147
What is pediculosis corporis?
Body lice
## Footnote
*Plural lice*
148
What is the medical term for lice?
Pediculosis
149
What causes pityriasis versicolour?
Malassezia
150
What is papular purpuric gloves and socks syndrome?
Rash most strongly associated with parvovirus B19
151
Which childhood exanthems may present with a strawberry tongue?
Scarlet fever
Kawasaki
152
What is the major complication of measles?
Subacute sclerosing panencephalitis
Dementia, myoclonus and epilepsy leading to coma and death
*7-10 years later*
153
Which paediatric exanthem is treated with vitamin A and why?
Prevention of severe exfoliative dermatitis in malnourished children with measles
154
Where does the rash of roseola originate?
Trunk
155
Which paediatric exanthem is more pronounced after exposure to sunlight or heat?
Erythema infectiosum
156
Which paediatric exanthems begins with a prodrome of acute tonsillitis?
Scarlet fever
157
What is the pathophysiology of parvovirus B19?
Binds to erythroid progenitor cells → cellular invasion → viral DNA enters the nucleus of erythroid cells → viral DNA replication → cytotoxicity → clinical manifestations + transient cessation of erythropoiesis
158
What are the features of parvovirus B19-associated arthritis?
Symmetrical, non-destructive
Small joints - fingers, hand, knee, ankle (similar to RA)
Self-resolving in most
159
Which patients develop a transient aplastic crisis with parvovirus B19 infection?
Patients with haematological conditions
Haemolytic: sickle cell disease, hereditary spherocytosis
Decreased production: iron deficiency anaemia, thalassemia
160
Which paediatric exanthem is non-infectious?
Kawasaki disease
Immune-mediated
161
What infection commonly proceeds guttate psoriasis?
Streptococcal pharyngitis
162
How is pediculosis corporis treated?
Washing/ironing clothes
Lice live and lay their eggs in clothes rather than on the body
163
What causes pruritis in scabies?
Excretions from mites and decomposing bodies → antigens → type IV hypersensitivity reaction → pruritus and excoriation
164
Which childhood exanthems may present with arthritis?
Parvovirus
Rubella
165
How can rubella and measles be differentiated?
166
What is the difference between a skin prick and skin patching?
Prick = IgE-mediated responses
Patch = allergic contact dermatitis
167
When is in vitro allergy testing preferred over skin pricks?
1. When the patient is on antihistamines
2. If skin testing carries a high risk of anaphylaxis
3. Comorbid dermatological conditions preclude testing e.g. severe atopic dermatitis
168
How are allergen immunoassays performed?
1. Serum is incubated with the allergen in question
2. Bound IgE is detected with an anti-IgE antibody
169
What causes bullous impetigo?
Staph - exfoliative toxins targeting desmogelin
170
How is scabies diagnosed?
Dermatoscopy
Skin biopsy
171
Which organism causes scabies?
Sarcoptes scabiei
